If you've ever played an MMO, most bosses or encounters have a "enrage" mechanic that will wipe the group if they can't master the mechanics necessary to win. This has been true in EVERY massive multiplayer game I've ever played that has been challenging and worth a damn. Allowing unlimited attempts / screw ups takes away from the experience and doesn't leaving you feeling like you've accomplished something.
I wouldn't consider those timers, they are simply mechanics that require near perfect / excellent execution.
Instead of everyone saying "it's too hard", people need to start looking at themselves and asking "how can I play / perform better"!
That seems like a stretch. Most (if not all) of the people commenting can complete the Nightfall and/or Raid under the dictated terms with plenty of time left. Perhaps it's not that we can't handle it, but that we find these particular methods of imposing challenge to be not fun?
Yes, that much is clear. However, the fact that others do not find it fun does not automatically mean "we can't handle a challenge."
It may mean nothing more than "this isn't something we enjoy doing." I mean, I'm not ashamed to say I'm certainly happier to do easy stuff for rewards than hard stuff. But if I'm doing hard stuff, I would like to have fun, rather than just (as someone else said) just be relieved when it's over.